Friday, February 4, 2011

Anaphylaxis

Remember this patient? After spending a couple of days at the referral hospital, undergoing numerous diagnostic tests including clotting times and an abdominal ultrasound, no underlying cause for her collapse was found. The presumptive diagnosis was as I had originally thought: anaphylaxis.

It occurred to me a moment ago that everyone might not be exactly familiar with the term or what it means.

Anaphylaxis is an acute, severe allergic reaction. If you've ever known someone with a life-threatening peanut or penicillin allergy, you are probably familiar with its effects. The onset is extremely rapid. A dog is exposed to something to which he is allergic. This could be a food substance, an insect bite, or something as innocuous as grass. In most cases, we never know the trigger. Mast cells and basophils (blood cells) release massive quantities of histamine. Histamine is a nasty substance and it is what ANTI-histamines like Benadryl, Zyrtec, and Allegra combat.

Histamine in large quantities causes the veins of the body to dilate, decreasing return of blood flow to the heart and causing a drop in blood pressure. Also, the small arteries of the body (arterioles) dilate, causing a further drop in blood pressure. Lastly, the smallest vessels in the body (the capillaries) become very permeable, and fluids and proteins move out of the cells and into the tissues of the body. This loss of protein into tissue also worsens the hypotension. Blood pressure plummets, heart rate sky rockets. The patient collapses, often developing diarrhea and vomiting.

The diarrhea and vomiting occur because the shock organ in the dog is the gut. It is the first place to suffer severe damage from decreased blood flow/blood pressure. Diarrhea and vomiting result. The diarrhea is often extremely thick and whitish, representing death of the lining of the intestines and sloughing of the cells.

Other substances elicited from the basophils and the mast cells called leukotrienes can cause spasms in the small airways (bronchioles). As a result, rapid, asthma-like symptoms and suffocation can occur.

Death can occur in a matter of minutes if a patient (human or animal) is not treated immediately with epinephrine. Epinephrine opposes the effects of histamine rapidly.

A dog that has suffered anaphylaxis usually presents very classically. They were totally normal, went outside, came back in, vomited, collapsed, and began to have labored breathing and/or diarrhea. Most dogs present in shock, but it is usually rapidly reversible with epinephrine and IV fluids to restore blood pressure.

As in the case of the unfortunate patient above, I believe if the owners had found her 10 minutes later, she would have been dead. Thankfully, she lives to fight another day!

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DISCLAIMER

Any similarity between my stories and any person or animal, living or dead, is strictly a coincidence. Names, breeds, sexes, and details of the stories have been changed to protect the guilty and innocent alike.

About Me

I am an emergency veterinarian in North Carolina. Despite the crazy people I deal with, the awful cases of injured and sick animals, and the overall stress of emergency work, I absolutely love what I do. Happily married since I was 20, I have a wonderful husband who has a PhD in Mathematics, and a daughter around whom our world currently revolves. We also have a zoo living in our house that can be alternately wonderful and maddening. There are cats, parrots, and a dog who is very low on the totem pole. Our days are never dull and we are learning to balance the demands of work and family.
If you'd like to contact me: homelessparrot@gmail.com

Human gross-ness

Followers

Medical terminology

Lactate - a salt/ester of lactic acid that is produced as energy for a cell when oxygen levels are low. In critically ill animals, elevated lactate can be an indicator of inadequate blood flow to organs (perfusion), decreased delivery of oxygen, and/or decreased oxygen uptake. Values > 6-7 are usually considered to be poor prognostic indicators for survival.

GI sloughing: when the cells lining the GI tract die (can be secondary to MANY things, including heatstroke) with resulting bloody diarrhea, bacterial translocation into the bloodstream and sepsis

TTJ: transfer to jesus: code for when an animal needs to be euthanized or die

DIC: disseminated intravascular coagulation: a very, very bad thing - when the hemostatic system gets out of whack, and clots start forming in the blood vessels until all clotting factors are wasted. once those are gone, internal hemorrhage ensues, followed by death, usually. also known as "death is coming"

Pleural effusion - fluid contained in the pleural space (chest) - this is not the same as fluid in the lungs (see pulm edema) - in cats can be caused by infection in the chest, heart failure, cancer, FIP, feline leukemia, FIV, and in some cases, the cause is never found (idiopathic)

Anisocoria - unequal pupil size (related to any number of causes including brain damage/head trauma)

Sepsis - refers to a bacterial infection in the bloodstream or body tissues. This is a very broad term covering the presence of many types of microscopic disease-causing organisms.

Nephrectomy - kidney removal

Splenectomy - removal of spleen

Pulmonary edema - condition in which fluid accumulates in the lungs, usually because the heart's left ventricle does not pump adequately ( can be caused by heart failure, electrocution, drowning, too many IV fluids, to name a few)

Tick borne diseases - any of a myriad of diseases transmitted by ticks - including but not limited to Rocky Mtn Spotted fever, Lyme disease, Ehrlichia

Fine needle aspirate - A method of sampling in which a needle is used to suck in cells or tissue bits for diagnoses (good for diagnosing masses/lumps)

Blood glucose - The principal sugar produced by the body from food–especially carbohydrates, but also from proteins and fats; glucose is the body's major source of energy, is transported to cells via the circulation and used by cells in the presence of insulin (normal range in a dog/cat is 75-100)

Diseases I see/treat frequently

Dystocia - difficulty birthing. May be responsive to oxytocin administration (Pitocin, as in people) but may require c-section.

DKA - diabetic ketoacidosis: the extreme end of the diabetic scale. A patient that is diabetic can develop DKA when other diseases make the blood glucose hard to regulate. Other diseases that are commonly associated include urinary tract infection, pancreatitis, pyometra, skin infection, and cancer. In DKA, the body starts metabolizing fat and producing acids that cause a drop in blood pH, nausea, weakness, severe dehydration, electrolyte derangments, and death.

DCM - dilated cardiomyopathy: an idiopathic (cause unknown) cardiac disease in which the heart chambers become very thin/dilated, and cardiac output drops radically. Causes arrhythmias, tachycardia, and sudden death. Seen in large breed dogs like Dobermans, Great Danes, etc.

Lymphoma - cancer of the white blood cells, the most common and treatable form of cancer in dogs

Blocked cat - slang term for a male cat with a plug of mucus and crystals obstructing the urethra (fairly common in male cats) definitely a life-threatening because urine can't get out of the body! If present long enough, causes shock, acute renal failure, hyperkalemia (elevated potassium), coma, and death. Symptoms include straining in the litterbox, yowling while trying to urinate, producing small, bloody drops of urine (also symptoms of feline cystitis, a non-lethal condition)

GDV - stands for gastric-dilatation and volvulus - a condition of large breed, deep-chested dogs (usually) in which the stomach rotates 180 degrees on its axis and thus - nothing can enter or leave, considered the "mother of all emergencies" - it warrants immediate surgery and carries a guarded prognosis

IMHA - immune-mediated hemolytic anemia. A disease in which the immune system attacks the red blood cells and destroys them. It causes profound anemia and is life-threatening. Causes are primary (no known cause) and secondary ( tick borne disease, cancer, and heavy metal intoxication). Treatment is immunosuppression with drugs primarily. Prognosis is guarded at best.